We propose to develop new, efficient and reliable non-invasive methods for the diagnosis of chromosomal aneuplodies. At present, the definitive diagnosis of chromosomal aneuploidies follows a two-step process: maternal screening and, if the results are positive, maternal amniocentesis with fetal karotyping. There are significant limitations to both first- and second-semester screening tests. It is clear that the detection rate for both screening methods gives a false impression of the overall accuracy of current screening tests, with the sensitivity and specificity of the tests resulting in too many false-positive results, thus exposing many pregnancies to an unnecessary 0.5%-1.0% risk of miscarriage. Furthermore, chromosomal analysis of amniotic fluid cells is a labor-intensive and time-consuming procedure, taking up to two weeks. More reliable tests are, therefore, necessary to improve the detection of chromosomal aneuploidies using maternal serum in order to reduce the unacceptably high false-positive rate of maternal screening and to increase the speed and efficiency of diagnosis from amniotic fluid following amniocentesis. We hypothesize that there are proteomic profiles present in the amniotic fluid or serum of mothers carrying fetuses with aneuploidies that can be utilized to develop a sensitive and specific diagnostic test that can replace the current generation of analytical choices. In this phase I application, we propose to identify, analyze, and validate proteomic profiles that consistently and reliably predict the presence of aneuploidy. We will employ a multi-pronged approach that involves surface-enhanced laser desorption-ionization/time-of-flight (SELDI-TOF), 2-dimensional gel electrophoresis, and isotope-coded affinity tagging (ICAT) techniques to identify proteins and peptides that are differentially expressed in amniotic fluid and/or maternal serum. Candidate biomarkers will be unambiguously identified by tandem mass spectrometry. The data obtained in this initial phase will provide the foundation for the development of a sensitive and specific high-throughput mass spectrometry-based diagnostic test. [unreadable] [unreadable]